Hi @brokenglass
When you save the map to disk from the map server by:
rosrun map_server map_saver -f <map_name>
two files will be generated.
Reference: http://wiki.ros.org/slam_gmapping/Tut...
A .pgm file that is a visual picture of the map and .yaml file that will contain information you are looking for. However you need to know how to interpret this information:
Reference: http://wiki.ros.org/map_server
The image describes the occupancy
state of each cell of the world in the
color of the corresponding pixel. In
the standard configuration, whiter
pixels are free, blacker pixels are
occupied, and pixels in between are
unknown. Color images are accepted,
but the color values are averaged to a
gray value.
You can take a look how map_saver.cpp does it. Some people use OpenCV to read image and interpret the occupancy map.
If you want to do something more advanced, take a look at this package: Grid Map by Anybotics
https://github.com/ANYbotics/grid_map
And the information on local planner and global planner parameters are stored as .yaml files.